1. Field of the Invention
The invention relates generally to a storage system and a management information acquisition method for power saving in the storage system, and more particularly to methods suitable for use in a power saving technique for the storage system.
2. Description of Related Art
Recently, the volume of data used by companies or individuals is increasing rapidly. Consequently, storage systems utilizing technology such as SAN (Storage Area Network) or NAS (Network Attached Storage), that connects storage subsystems to host computers using switches or hubs and enables flexible data management, are widely used.
Meanwhile, since the scale of storage subsystems is increasing and their performance is being enhanced, power consumption in storage subsystems is also increasing. Accordingly, power saving in storage subsystems is being considered as more and more important.
There is a technique for achieving power saving in a storage system by setting, if a host computer that utilizes a storage region (hereinafter referred to as “volume”) in a storage subsystem does not access the volume for a predetermined period of time, the power supply for the physical disks that compose the volume to ‘off’ or ‘suspended’ mode (hereinafter referred to collectively as “sleep mode”), and cancelling the sleep mode in the physical disks and returning them to regular power mode when the volume is accessed, thus controlling the power consumption in the storage subsystem.
For example, Japanese Patent Laid-Open Publication No. 2005-157710 discloses a technique for controlling, according to an order from a computer connected to a storage subsystem, power on/off in physical disks that compose a volume a storage subsystem provides.
Generally, there is a system configuration of storage system management in which an agent program for monitoring information about volumes used by a host computer is provided to the host computer to regularly acquire the information. If the above conventional technique is used in that system configuration, the agent program in the host computer cannot recognize that the physical disks are in sleep mode when the power supply for the physical disks included in the storage subsystem is set to sleep mode. Therefore, the agent program regularly accesses the physical disks regardless of power mode in the physical disks to acquire the volume information.
However, the volume information does not change while the physical disks are in sleep mode. In the conventional technique, the agent program in the host computer regularly accesses the physical disks to acquire information even though the information does not change. As a result, the sleep mode in the physical disks is frequently cancelled and power consumption in the storage subsystem increases.
An object of the invention is to provide a storage system and a management information acquisition method for power saving in a storage subsystem, the storage system being one in which the physical disks are not accessed while the power supply state in the physical disks is in sleep mode, so the sleep mode in the physical disks does not have to be unnecessarily cancelled and power consumption in the storage subsystem can be controlled.